Encoding data in email headers

ABSTRACT

Among other things, we describe techniques for encoding data that is included in electronic communications. In one aspect, a first electronic communication system sends, to an entity, a first email message that includes a Message-ID field including data that identifies an action to be carried out by a second electronic communication system. The first electronic communication system receives, from the entity, a second email message that includes an In-Reply-To field containing the data that identifies the action to be carried out by the second electronic communication system. The first electronic communication extracts the data from the In-Reply-To field in a message header of the first electronic communication. The second electronic communication system may be the same as the first electronic communication system, or may be an electronic communication system other than the first electronic communication system.

BACKGROUND

This description relates to encoding data in email headers. Electronicdevices can be used to communicate information with other electronicdevices using a variety of protocols. As an example, electronic mail(email) is a message-exchange framework that is commonly used on theInternet and other communication networks.

SUMMARY

The encoding data in email headers that we describe here may encompassone or more of the following (and other) aspects, features, andimplementations, and combinations of them.

In general, in an aspect, a method includes, at a first electroniccommunication system, sending, to an entity, a first email message thatincludes a Message-ID field containing data that identifies an action tobe carried out by a second electronic communication system. The methodalso includes receiving, from the entity, a second email message thatincludes an In-Reply-To field containing the data that identifies theaction to be carried out by the second electronic communication system.The method further includes extracting the data from the In-Reply-Tofield in the message header of the second email message.

In some implementations, the second electronic communication system isthe same as the first electronic communication system. In someimplementations, the second electronic communication system is anelectronic communication system other than the first electroniccommunication system.

Implementations of this aspect may include one or more of the followingfeatures. Receiving an indication to associate the action with the firstemail message, and generating the first email message including thedata. Carrying out the action based on the data extracted from thesecond email message. The action to be carried out by the secondelectronic communication system was defined based on input received froma user, and the content of the first email message was defined based oninput received from the user.

In general, in another aspect, a method includes, at an electroniccommunication system, receiving a first electronic communication from afirst entity, the first electronic communication including datarepresentative of an action to be carried out by the electroniccommunication system, the data having been previously generated by theelectronic communication system and included in a second electroniccommunication previously sent to the first entity.

Implementations of this aspect may include one or more of the followingfeatures. Receiving an indication to associate the action with anelectronic communication, and generating the second electroniccommunication including the data. The action to be carried out by theelectronic communication system was defined based on input received froma first user, and the content of the second communication was definedbased on input received from the first user. The first electroniccommunication comprises a first email message and the second electroniccommunication comprises a second email message, and the datarepresentative of an action to be carried out is included in at leastone of the following header fields of the first email message or thesecond email message: “Message-ID,” “In-Reply-To,” “From,”“Resent-From,” “Reply-To,” “To,” “Cc,” “Bcc,” “Resent-To,” “Resent-Cc,”“Resent-Bcc,” or “References.”

In general, in an aspect, a first electronic communication systemincludes one or more computers and one or more storage devices storinginstructions that are operable, when executed by the one or morecomputers, to cause the one or more computers to perform operations thatinclude sending, to an entity, a first email message that includes aMessage-ID field including data that identifies an action to be carriedout by a second electronic communication system. The operations alsoinclude receiving, from the entity, a second email message that includesan In-Reply-To field containing the data that identifies the action tobe carried out by the second electronic communication system, andextracting the data from the In-Reply-To field in a message header ofthe first electronic communication.

In general, in another aspect, an electronic communication systemincludes one or more computers and one or more storage devices storinginstructions that are operable, when executed by the one or morecomputers, to cause the one or more computers to perform operations thatinclude receiving a first electronic communication from a first entity,the first electronic communication including data representative of anaction to be carried out by the electronic communication system, thedata having been previously generated by the electronic communicationsystem and included in a second electronic communication previously sentto the first entity.

In general, in another aspect, at least one computer-readable storagemedium encoded with at least one computer program includes instructionsthat, when executed, operate to cause at least one processor in a firstelectronic communication system to perform operations that includesending, to an entity, a first email message that includes a Message-IDfield including data that identifies an action to be carried out by asecond electronic communication system. The operations also includereceiving, from the entity, a second email message that includes anIn-Reply-To field containing the data that identifies the action to becarried out by the second electronic communication system, andextracting the data from the In-Reply-To field in a message header ofthe first electronic communication.

In general, in another aspect, at least one computer-readable storagemedium encoded with at least one computer program includes instructionsthat, when executed, operate to cause at least one processor in anelectronic communication system to perform operations includingreceiving a first electronic communication from a first entity, thefirst electronic communication including data representative of anaction to be carried out by the electronic communication system, thedata having been previously generated by the electronic communicationsystem and included in a second electronic communication previously sentto the first entity.

These and other aspects, features, and implementations, and combinationsof them, may be expressed as apparatus, methods, methods of doingbusiness, means or steps for performing functions, components, systems,program products, and in other ways.

Other aspects, features, and advantages will be apparent from thedescription and the claims.

DESCRIPTION

FIGS. 1, 2A, 2B, 2C, 2D, 3A, 3B and 8 are block diagrams.

FIGS. 4, 5 and 6 are flow charts.

FIG. 7 is a sketch of an example of a user interface.

An electronic communication system can encode data in an electronicmessage that will be included in subsequent messages transmitted byother electronic communication systems.

Electronic communication systems enable different entities tocommunicate, handle and process electronic communications. Various typesof electronic communication exist, using various types of electroniccommunication protocols. An electronic communication may include varioustypes of content, such as text, data, voice, images, video, etc. Anelectronic communication can be transmitted and received between varioustypes of electronic communication systems, such as personal desktopcomputers, server computing systems, mobile computing devices, etc. Anexample of a type of electronic communication is an email message. Anemail message has at least one receiving entity, and can have multiplereceiving entities.

The term entity is used herein in a broad sense, and includes individualusers or groups of users, such as an organization. An entity istypically associated with an electronic communication address, such asan email address, which can be used by other entities to send electroniccommunications to the entity. An email address can be associated with asingle user, or an email address may be associated with a group ofpeople, such as an organization or a mailing list.

There are different types of electronic communication systems that canbe used to send and receive electronic communications. For example, anemail application running on an entity's computing device (often calleda “client”) allows the entity to interact with an email system, whichcarries out the actions of sending and receiving email messages sent toand from a variety of entities on a variety of computer systems (e.g.,personal computers, smart phones, tablet computers, and other types ofcomputer systems). An email system can run on one or more servers andprovide various email services to the email applications running onclients. An email system typically operates according to standardizedemail protocols for sending and receiving messages. Typical emailprotocols include SMTP, POP3, and IMAP.

In some examples, email applications can be accessed using variousapplication interfaces. In some examples, email applications areaccessed using a web browser interface, a custom application interface(e.g., a dedicated email application or a file system interface of anoperating system), a general use mobile application (e.g., emailapplication), a specialized use mobile application (e.g., custom mobileapplication written for use with a particular system), or another kindof interface. In some examples, the application interface may be anapplication programming interface (API) that interacts with softwarecomponents. In some examples, an API can be programmed to automaticallyaccess the email application and to perform certain actions based oncontents of received email messages.

There are various ways that entities can send, received, handleelectronic communications. For example, if the electronic communicationis an email message, then the exchange and handling of email messagesfollows one or more standards, such as those defined by the InternetEngineering Task Force (IETF). For example, an entity can send identicalcopies of an email message to multiple receiving entities. This can beachieved by directly addressing the email message to multiplerecipients, and/or by using “carbon copy” or “blind carbon copy,” thelatter being used to hide the identity of one or more recipients fromother recipients. In some examples, an entity that receives an emailmessage can forward it to other entities, by sending a new email messagethat includes the text of the original message. In some examples, anentity may classify, into sub-categories or folders, different emailmessages that the entity had previously sent and/or received.

The system and techniques that we describe here can be implemented toenable an entity sending an electronic communication to include encodeddata into the electronic communication in such a way that the encodeddata is automatically preserved in subsequent electronic communicationsthat are replies to and/or forwards of the electronic communication. Theencoded data may encode an action, selected by the entity, to beperformed upon receiving a subsequent reply and/or forward of theelectronic communication. An action to be carried out by an electroniccommunication system may be defined based on input received from a user.In some examples, an action may have been defined directly based on aninput by a user (e.g., by an individual user or by a user among a groupof users, e.g., an organization) who specifies that the action is to beencoded into encoded data that is included in the particular outgoingelectronic communication. In some examples, an action may have beendefined indirectly based on an input by a user who specifies the actionas part of an automated process that encodes the action into encodeddata that is included in multiple outgoing electronic communications,which includes the particular outgoing electronic communication.

By “encoded data,” we mean any data that is encoded (e.g., formatted) ina manner that can be included in an electronic communication. The mannerin which the data is encoded may depend on the format of the electroniccommunication, or characteristics of the data to be encoded, and/orother factors. We sometimes describe “encoding” or “decoding” the data,which refers to formatting the data (e.g., putting the data in a formatsuitable for transmission) or interpreting the data (e.g., identifyingcontents of the encoded data).

In some implementations, the encoded data may be included in portions ofan electronic communication that are automatically extracted and thenincluded in subsequent electronic communications by other entities, evenif the other entities are unaware of, or unable to access, the encodeddata. In some implementations, the encoded data may be encrypted so thatthe encoded data is not accessible to entities for whom the encoded datais not intended. Regardless of whether an entity is aware of, or is ableto access, encoded data that is included in an electronic communication,an electronic communication system operated by the entity mayautomatically extract and include the encoded data in subsequentelectronic communications. As such, the system may require no clientside changes on the part of an entity replying to or forwarding theelectronic communication that contains the encoded data.

In some implementations, the encoded data could be included in standardheader fields of an email message. By “standard header fields,” we meanheader fields defined by standards for electronic communication. Theheader fields could be defined by appropriate IETF standards, such asRequest for Comments (RFC) 822 and Multipurpose Internet Mail Extensions(MIME). As examples, such header fields could be, but are not limited tomessage originator header fields (e.g., “From,” “Resent-From,”“Reply-To”), or message recipient header fields (e.g., “To,” “Cc,”“Bcc,” “Resent-To,” “Resent-Cc,” “Resent-Bcc”), or message-id relatedheader fields (e.g., “Message-ID,” “In-Reply-To,” “References”). Whenthe encoded data is included in such header fields of an email message,recipient email clients and/or servers will extract and include theencoded data in subsequent replies and/or forwards, even withoutnecessarily being aware of the presence of the encoded data in theheader fields and/or without having any functionality specific toencoding or decoding the data.

Communication systems other than email systems may also support headerfields that can be used in this same way. For example, communicationsystems used for text messages (e.g., Short Message Service [SMS]),instant messages (Extensible Messaging and Presence Protocol [XMPP]),and multimedia messages (e.g., Multimedia Message Service [MMS], andSession Initiation Protocol [SIP]) may support or can be modified tosupport header fields that can be used in this way.

In some implementations, the encoded data may be secure from access byunauthorized entities. For example, the encoded data may be encryptedand the email message header may include authentication credentials,such as an electronic signature, that relates the encoded data to theidentity of an authorized entity (e.g., the entity that included thedata, or another entity for whom the encoded data is intended).

In some implementations systems that utilize such encoded data may bestateless, in the sense that separate storage for system state may notbe needed in order to process the instructions in the encoded data.Instead, all the information needed to perform the desired action isencoded in email message headers such as the headers described above. Insome examples, this stateless feature can enable systems to scale tolarger dimensions without a necessarily requiring a corresponding growthin storage facilities for maintaining state to match receivedinformation to desired instructions. In some implementations, this mayfacilitate deployment in large communication networks with a largenumber of users. In some implementations, some state information couldbe stored and remain persistent between multiple email messages, tofacilitate interpreting the encoded data extracted from email messageheaders. For example, a message header field may include a database keythat enables an entity to access a database to retrieve instructions toperform. In some implementations, this may be added for securityreasons, because even if an unauthorized entity were to extract adatabase key, the unauthorized entity may not be able to access thedatabase for which the key is intended (e.g., if the database is localto the intended entity, if the database has security features limitedaccess, etc.).

Independent of the content of the data that is encoded in the electroniccommunication, and independent of whether that information is completelyself-contained in the electronic communication or accessible via storedstate information, the encoded data can be included in electroniccommunications in such a way that it is automatically preserved insubsequent replies to and/or forwards of the electronic communication ,even if the replying and/or forwarding entities are not aware of, or notauthorized to access, the encoded data.

Such techniques can be applied to other types of electroniccommunication and electronic communication protocols, other than email.For example, if another type of electronic communication has a portionof the electronic communication that is automatically extracted andincluded in subsequent electronic communications that are in reply to,or forwards of, the electronic communication, then techniques describedhere can be used to include encoded data into the electroniccommunication in such a way that the encoded data is automaticallyincluded in the subsequent electronic communications.

FIG. 1 is a block diagram of an example communications system 100 thatenables entities to include encoded data into electronic communicationsin such a way that the encoded data is automatically and securelypreserved in subsequent electronic communications sent by otherentities, according to some implementations. An entity, such as the user102, exchanges electronic communications, such as emails 104 a, 104 b,with other entities, such as another user 106, or a third user 108, oran organization 110. The communication is enabled by a communicationnetwork, such as the network 112, which can be the Internet, a localarea network (LAN), or any appropriate communication network. The user102 can use a computing system 114, such as a personal computer, laptop,portable device, or any other computing system, to send and receiveemails. A user 102 using the computing system 114 can send and receiveemails by using a client email application installed on the computingsystem 114, or by using an interface, such as a web browser, to access aremote email server that performs the sending and receiving.

In some implementations, if the computing system 114 of the user 102includes encoded data in an outgoing email message 104 a sent to anotheruser 106, then the encoded data that was included in the email message104 a can be automatically returned to the user 102 in a subsequentreply email message 104 b sent by the other user 106, without the otheruser 106 even being aware of the presence of the encoded data. Theencoded data can be any data that the user 102 wishes to include thatcan be decoded by a communication system, such as data that indicates anaction to be carried out by the computing system 114 of the user 102upon receiving the reply email 104 b. In some implementations, thecomputing system 116 of the other user 106 receiving the original emailmessage 104 a can also be made aware of, and allowed to extract, theencoded data included in email message 104 a. In such cases, thecomputing system 116 of the other user 106 can also use the encoded datato perform any action that is indicated by the data.

As another example, the computing system 114 of the user 102 can includeencoded data in the outgoing email 104 a to the other user 106 in such away that the encoded data is automatically included in any subsequentforwards of the email message 104 a by the computing system 116 of theother user 106. For example, if the other user 106 receives the emailmessage 104 a and forwards it in another email message to the third user108, then the encoded data that was included in the original emailmessage 104 a can be automatically carried over to the forwarded emailmessage by the computing system 116 of the other user 106. Theforwarding user 106 need not necessarily be aware of the presence of theencoded data that was carried over but can, in some implementations, beallowed to extract and process the encoded data. The third user 108,upon receiving the forwarded email message containing the encoded data,can extract the encoded data from the forwarded email message andperform any appropriate action indicated by the data.

As another example, an entity, such as the organization 110, can use thetechniques described here to enable features of email communication withentities external to and within the organization 110. The organization110 can utilize a computing system, such as email server 120, to handlethe sending and receiving of email messages on behalf of other entitieswithin the organization 110, such as a first user 122 a and a seconduser 122 b. The email server 120 and the first and second users 122 aand 122 b can communicate using any communication network, either wiredor wireless, within the organization 110.

The organization 110 may use a single email address, such as“info@company.org,” to communicate with entities external to theorganization 110. In some implementations, data can be encoded inoutgoing emails from that email address, and be extracted from incomingreplies to route emails sent to the generic email account to the rightperson within the organization 110. Thus, the organization 110 couldhandle replies sent to a single generic email address in different ways.

This may also be used in situations where external anonymity of entitieswithin an organization, is desired. For example, in FIG. 1, entitiesthat are external to the organization 110 could communicate with thefirst and second users 122 a and 122 b via a single generic emailaddress associated with organization 110, without necessarily knowingthe individual email addresses of each of the first and second users 122a and 122 b. This “single-address” technique could also enable anonymousor pseudonymous emailing, in which replies to a single email address canbe selectively routed to different people based on the encoded datareceived in the reply emails.

As one example of enabling this single-address technique, the server 120could include different types of encoded data in the header of anoutgoing electronic communication, such as email message 124 a. As anexample, the encoded data could depend on the nature of the outgoingemail 124 a, such as whether the email relates to a promotional event,or relates to an account billing issue. When an external recipientreplies to the email 124 a, then the reply email 124 b will include thesame encoded data that was in the outgoing email 124 a, without theexternal recipient necessarily being aware of the presence of theencoded data. The received email 124 b can be processed by the emailserver 120, the encoded data can be extracted, and the server 120 canperform any action based on the encoded data. For example, the email canbe routed to an appropriate entity within the organization 110. In theexample of FIG. 1, if the encoded data indicates that the original email124 a related to a promotional event, then the server 120 can forwardthe reply email 124 b to the first user 122 a (e.g., who may be anentity in charge of public relations within the organization 110), andif the encoded data indicates that the original email 124 a related toan account billing issue, then the server 120 can forward the replyemail 124 b to the second user 122 b (e.g., who may be an entity incharge of finance within the organization 110).

In some implementations, entities within the organization 110, such asthe first and second users 122 a, 122 b, may include encoded data in anemail header to indicate that the email message should not be forwardedoutside of the organization 110. This may be chosen by the entities, forexample, if the email message contains information that is confidentialto the organization 110. For example, an email message sent by the firstuser 122 a and received by the second user 122 b may include encodeddata indicating that the email message should not be forwarded outsidethe organization 110. If the second user 122 b subsequently forwards theemail message to other entities, and if one of those other entities isoutside of the organization 110, then the server 120 can receive theforwarded email message, extract the encoded data, determine that theemail message should not be forwarded outside of the organization 110,and block the forwarding of the email message outside of theorganization 110.

The extracted data can be used by entities for a variety of purposes,and the system described here is not limited to any particular purpose.The data can be used to indicate that an entity extracting the datashould perform any appropriate action upon receiving an email containingthe encoded data. Such actions can include, for example, changing acharacteristic of one or more email messages, implementing rules forhandling one or more email messages, or the data may not relate to emailcommunication at all, and may be used for other purposes. Furtherexamples and explanations are provided below, e.g., in the descriptionsof FIGS. 2C, 2D, and 7.

Independent of the instructions represented by the encoded data, thesystem described here can be used to include the encoded data in anemail message in such a way that the encoded data is automaticallycarried over to subsequent replies to and forwards of the email messageby other entities, even without the other entities necessarily beingaware of the presence of the encoded data. Such a system may enableexpanded features and capabilities for users of an email system.

FIGS. 2A-2D illustrate examples of sending, receiving, and extractingdata that is encoded in email headers, and taking actions based on theextracted encoded data, according to some implementations. In theseexamples, an entity's email client that includes and sends encoded datain an email message is also the email client that extracts the encodeddata from a subsequent reply email and performs an action based on theextracted encoded data. The sender is only one example of an entity thatmay extract and use the encoded data, and other entities besides thesender may extract and use the encoded data. For example, if thesender's email message is forwarded to other users, then the encodeddata will automatically be included in the forwarded emails, and theemail clients of one or more of the users that receive the forwardedemails may extract and process the encoded data to perform actions thatwere indicated by the original sender.

Although the examples in FIGS. 2A-2B are described in the context ofincluding encoded data in the Message-ID and In-Reply-To header fieldsof an emails message, these techniques are not limited to using theseparticular header fields. For example, a number of header fields (e.g.,header fields such as those defined by the communication standardsdescribed above) may be used to persistently carry the encoded data inan email message and subsequent replies to, and forwards of, the emailmessage. Examples of other header fields are provided below in thedescription of FIGS. 3A-3B.

In FIG. 2A, a first user 200 communicates with a second user 202 viaelectronic communication, such as a first email message 204 a. Prior tosending the first email message 204 a, the first user 200 may select aparticular action to be taken when a subsequent reply of the first emailmessage 204 a is received by the first user 200 from the second user202. Additionally or alternatively, the action may be taken by thecomputing system of a third user that receives a subsequent forward ofthe first email message 204 a from the second user 202.

In some implementations, the encoded data can be included in a standardheader field of an email message by the email client of the first user200. The encoded data can be included in the standard header field insuch a way that replies to and/or forwards of the email message willautomatically include the same encoded data in a corresponding headerfield of the reply/forward email message, even if thereplying/forwarding entity is not aware of the presence of the encodeddata.

As an example, email systems that conform to IETF-published standardstypically have a “Message-ID” field in the header of an email message.The Message-ID field contains a globally unique identifier (e.g., aserial number) for the email message. The contents of the Message-IDfield are automatically carried over by IETF-compliant recipient emailclients into the “In-Reply-To” field of any reply emails and forwardemails of the email message. In this way, email clients can identifyemail messages belonging to the same thread of conversation.

FIG. 2B illustrates how this feature of IETF-compliant email clients canbe utilized by the email client of the first user 200, so that when thefirst user 200 includes encoded data 208 into the Message-ID field 206 aof the first email message 204 a to a second user 202, that encoded data208 will be automatically returned in the In-Reply-To field, such asIn-Reply-To field 206 b, of a subsequent reply email message, such assecond email message 204 b. The email client of the first user 200 caninsert the encoded data 208 into the Message-ID field 206 a using anyone of various insertion techniques, some of which are described belowwith respect to FIGS. 3A and 3B.

After the second user 202 receives the first email message 204 a fromthe first user 200, the entire contents of the Message-ID field 206 aare automatically extracted by an IETF-compliant email client of thesecond user 202 and automatically included in the In-Reply-To field 206b of the second email message 204 b, sent by the second user 202.Included in the contents that are automatically included in theIn-Reply-To field 206 b of the second email message 204 b is the encodeddata 208. The transfer of the contents of the Message-ID field 206 a,including the encoded data 208, from the first email message 204 a tothe In-Reply-To field 206 b of the second email message 204 b occursautomatically by the IETF-compliant email client of the second user 202,even if the email client of the second user 202 is unaware of thepresence of the encoded data 208. When the first user 200 receives thesecond email message 204 b, the email client of the first user 200 canbe configured to extract the encoded data 208 from the In-Reply-To-Field206 b, and take an appropriate action that is indicated by the encodeddata 208.

As another example, FIG. 2C illustrates an example of the encoded data208 being carried over from the first email message 204 a to theIn-Reply-To field 206 c of a third email message 204 c, forwarded by thesecond user 202 to a third user 210. In this case, the third user 210may extract and process the encoded data 208 to take an appropriateaction indicated by the first user 200. In some implementations, theintermediate forwarding entity, such as the second user 202 (e.g., acomputer system and/or email client operated by the second user 202),need not necessarily be aware of the presence of the encoded data 208that was forwarded to the third user 210.

Therefore, the first user 200 may include encoded data 208 (e.g., databeyond simply identifying the message, such as data indicating an actionto be carried out) in the Message-ID field 206 a of the first emailmessage 204 a, and the encoded data 208 will be automatically beextracted by an email client of the recipient (e.g., second user 202)and copied into the In-Reply-To field of subsequent reply and/or forwardemail messages (e.g., the In-Reply-To field 206 b of the second emailmessage 204 b in FIG. 2B, or the In-Reply-To field 206 c of the thirdemail message 204 c in FIG. 2C).

In some implementations, an email message header field, such asMessage-ID field 206 a, can further include mechanisms to secure encodeddata, e.g., the encoded data 208. Such security mechanisms may be usedto prevent re-use of Message-ID headers to perform undesired actions. Insome implementations, systems can use an encryption scheme to ensurethat an email message header field, such as Message-ID field 206 a,cannot be modified without destroying the encoded data. In someimplementations, systems can embed certain validation information in themessage header field so that the header field is only valid when sent toan authorized entity. For example, the Message-ID field 206 a cancontain a security mechanism, such as an electronic signature 212, thatties the encoded data 208 to an identifying mechanism, such as a key214, belonging to an authorized recipient of the encoded data 208, suchas the first user 200 (in FIG. 2B) or the third user 210 (in FIG. 2C) orany other intended recipient of the encoded data 208.

In this way, the encoded data 208 can be automatically and securelyextracted and replicated by email systems, even systems that may not beconfigured to process, nor even to be aware of, the encoded data that isincluded in the header fields of the email message. By using existingheader fields of email messages and existing mechanisms thatautomatically extract and relay information contained in those headerfields, the need for customized solutions may be reduced, resulting in asimplified and scalable system. Moreover, by enabling secure andconfidential transport of encoded data within email header fields, theencoded data can, in some implementations, be detailed enough touniquely define an action to be carried out by the extracting entity. Insome examples, the encoded data can define a particular context in whichthe action is to be carried out. In some implementations, suchtechniques may not necessarily require additional databases, servers, orother components to store additional information to interpret theencoded data. In some implementations, some state information may bestored and retrieved by entities, for example, to assist in interpretingthe encoded data and performing the intended instruction.

FIG. 2D illustrates examples of different actions that can be enabled bythe encoded data 208 that is extracted by an authorized user 216 (e.g.,the first user 200 in FIG. 2B or the third user 210 in FIG. 2C), fromthe In-Reply-To field 206 b of a reply/forward email message 218 (e.g.,the second email message 204 b in FIG. 2B or the third email message 204c in FIG. 2C) containing the encoded data 208 that is received by theauthorized user 216. For example, the authorized user 216 may want thereply/forward email message 218 to be placed in a certain folder, suchas folder 220, in an email archive. Information identifying the folder220 can be embedded in the encoded data 208 in a header field of theemail message 218, so that an email client of the authorized user 216can be configured to extract and process the encoded data 208 toautomatically place the received email 218 in the folder 220.

As another example, the authorized user 216 (e.g., the first user 200 inFIG. 2B or the third user 210 in FIG. 2C) can use the encoded data 208to automatically relate the received email message 218 (e.g., the secondemail message 204 b in FIG. 2B or the third email message 204 c in FIG.2C) to one or more other email messages that were previously sent and/orreceived by the authorized user 216. If the authorized user 216 sends aseries of related emails to one or more recipients, then the authorizeduser 216 may wish to group and match the related emails together.Furthermore, if one or more of the recipients respond, then theauthorized user 216 may want to match the replies together and/or matchthe replies against other related emails. Using the techniques describedhere, the authorized user 216 can include identifying information in theencoded data 208 to allow tracking these apparently independent emailstogether. In addition to using standard message header fields (e.g.,Message-ID, In-Reply-To, Subject, etc.) to group and track threads ofemails, such techniques can group together related emails from differentthreads and perform common actions on those related emails (e.g., filingthe related emails in a common directly, or tagging the related emailswith a common tag, etc.) A client and server can be configured toimplement these techniques; for example, the client and/or server couldautomatically group the related emails in a way that may not beotherwise possible without human effort, which may be prone to errors.The configured client and/or server would be able to match the repliesfrom any of the related emails together and provide a richer set offeatures. In this way, the techniques described here can be used tomatch not only clearly-related emails (e.g., replies and forwards ofemails), but also to match emails that are less-obviously related, suchas emails for a common topic, client, or work product.

The examples described here are of possible uses of the techniquesdescribed herein. In general, data that is encoded in email messageheaders, such as the encoded data 208 shown in FIGS. 2A-2D, can be usedto embed any information or action (e.g., action to be executed by acomputer system) into the email message. The information or action cantake any form, e.g., can be chosen by entities that include the encodeddata into email messages, such that the action is automaticallyperformed by an authorized entity that extracts the encoded data. Otherexamples of actions that may be encoded are presented below in thedescription of FIG. 7.

FIGS. 3A and 3B illustrate examples of email message headers thatinclude encoded data, according to some implementations. An electroniccommunication typically includes multiple portions of information. Someportions of the electronic communication may be used for carryinginformation to be communicated to other entities, while other portionsof the electronic communication may be used for carrying informationrelated to the control and routing of the electronic communication.

For example, an email message, such as a first email message 300 a inFIG. 3A and a second email message 300 b in FIG. 3B, consists of amessage header, such as first and second message headers 302 a and 302b, and a message body, such as first and second message bodies 304 a and304 b. The first and second message bodies 304 a and 304 b typicallycontain information that is to be communicated between entities, and thefirst and second message headers 302 a and 302 b typically containcontrol information for routing and handling the email messages. Thefirst and second email messages 300 a and 300 b may also have variousattachments to the email messages and/or in-line objects embedded withinthe email messages.

The first and second email message headers 302 a and 302 b containvarious header fields that define control information, such as “From”and “To” fields that contain originator and recipient email addresses,respectively, a “Date” field that contains a date/time stamp, and a“Subject” field that contains a subject of the email message. Inaddition, the first email message header 302 a may contain a “Bcc” fieldindicating one or more entities to whom the first email message 300 ashould be sent as a “blind carbon copy,” e.g., without indicating toother recipients that those one or more entities were copied.

The first and second email message headers 302 a and 302 b also havefirst and second Message-ID fields 308 a and 308 b, respectively, whichuniquely identify the first and second email messages 300 a and 300 b.In general, the first and second email message headers 302 a and 302 bmay also have other fields not shown in FIGS. 3A and 3B, such as messageoriginator header fields (e.g., “From,” “Resent-From,” “Reply-To”), ormessage recipient header fields (e.g., “To,” “Cc,” “Bcc,” “Resent-To,”“Resent-Cc,” “Resent-Bcc”), or message-id related header fields (e.g.,“Message-ID,” “In-Reply-To,” “References”). Techniques described hereincan be used to include encoded data, such as encoded data 310, into anyappropriate message header field, such as the first Message-ID field 308a, such that the encoded data 310 is automatically included in a headerfield of a reply/forward email message, such as the In-Reply-To field312 of the second email message 300 b.

Although the examples in FIGS. 3A and 3B show the encoded data 310 beingincluded in the first Message-ID field 308 a of the first email message300 a, and in the In-Reply-To field 312 in the second message header 302b of the second email message 300 b, implementation are not limited tousing these particular fields, as any of the above-listed header fieldsmay be appropriately used to carry the encoded data 310 in a persistentmanner between an email message and replies/forwards of the emailmessage.

The encoded data 310 can be included in the header fields in any manner.In some implementations, if the encoded data is included in a fieldnormally reserved for email addresses (e.g., From, Reply-To,Resent-From, To, CC, BCC, Resent-To, Resent-CC, etc.), then in the localpart of the email address, one or more separating characters (e.g., a“+” symbol or other suitable separating character(s)) could be used toseparate the actual delivery email address from the encoded data, suchas encoded data 310. For example, an email message with a “To” headerfield specifying “nsb+data@company.org” would be routed to the emailaddress “nsb@company.org,” but the “data” part would be available forextracting and processing by authorized entities to perform thespecified action. In some implementations, if the encoded data isinclude in non-addressing header fields (e.g., Message-ID orIn-Reply-To) then one or more separating characters (e.g., a “+” symbol)could also be used to separate the encoded data from other informationin the header fields.

The particular format of the encoded data, such as encoded data 310, canbe any format used to encode data. For example, a base64 encoding ofcompressed and encrypted JavaScript Object Notation (JSON) could beused. But any format of the encoded data 310 could be used, for example,Extensible Markup Language (XML), a serialized Java objects, raw bytes,etc. An encoding, such as a base64 encoding, could be used to convertthe information in the encoded data 310 from binary format to a formatthat RFC-compliant systems can recognize. In some implementations,compression could be used to achieve compactness of the encoded data310, but may not be necessary, for example, if the encoded data 310 issmall. In some implementations, the encoded data 310 could be encryptedto make it secure, though this may not be necessary if the encoded data310 is not confidential.

Any type of data (and associated action) can be encoded and included inemail message headers. As examples, the encoded data could indicate anautomated action. For example, the encoded data could indicate an actionto be performed when the message is replied to. In this example, thesender of the message could tell the recipient, “if you want to performaction X, then just reply to this email message.” As another example ofan automated action, the encoded data could indicate that when anassociated thread of messages has been completed (e.g., after an amountof time has elapsed since the most recent message in the thread), aparticular individual could be notified. As another example, the encodeddata could indicate a selective distribution of the email message (e.g.,user 2 attempts to forward an email message to user 3, but the encodeddata in the email message instructs user 2's email client/server not todeliver to user 3). As another example, the encoded data could indicateselective arrival notification (e.g., if a recipient of an email messageforwards the email message to another user, then the original sender ofthe email message is notified). As another example, the encoded datacould indicate instructions related to certain aspects of a user'scomputing environment (e.g., if user 1 sends an email message to user 2,when user 2 reads the email message, then user 2's email client/servercould automatically open applications (e.g., documents, web pages, etc.)that were open on user 1's screen and that user 2 is allowed to see). Asyet another example, the encoded data could include whitelistinginformation. For example, user 1 could specify authenticationinformation, e.g., listed on user 1's business card or in a publicdirectory of authentication information, that, when included in encodeddata that is included in an email message sent to user 1, indicates thatthe email message should be accepted by an email client/server of user1. In this example, an email server that receives messages sent to user1 can filter incoming messages based on the presence of theauthentication information.

Regardless of the exact nature of the encoded data, or the specific wayin which the encoded data is included in an email message header, anentity can have the encoded data included in an outgoing email, in sucha way that the encoded data is automatically included in subsequentemails that are in reply to, or forwards of, the outgoing email. In someimplementations, the encoded data can be included in an email message insuch a way that even if the receiving entity's email client or server isnot explicitly aware of the presence of the encoded data, the encodeddata is nonetheless automatically extracted by the client or server andincluded in subsequent replies to and/or forwards of the email message.

The encoded data may be defined by a person, an email client, an emailserver, or any other entity. In some implementations, the encoded datacan be encrypted to prevent unauthorized access to the data, even byentities that receive and handle email messages containing the encodeddata. For example, the encoded data can be encrypted so that the encodeddata is only interpretable by the sender of the original message, or byone or more of the recipients of email messages that are replies toand/or forwards of the original message. In such a way, the encoded datacan include confidential information that can be securely sent,returned, and forwarded among different entities.

FIGS. 4-6 are flowcharts of examples of processes of encoding, sending,and extracting encoded data from electronic communications. Although theexamples in FIGS. 4-6 illustrate certain scenarios, e.g., of an entitysending the encoded data and subsequently receiving back the encodeddata in a reply (e.g., the second email message 204 b in FIG. 2B),implementations are not limited to the encoded data being included in,and/or extracted from, replies. In some implementations, the encodeddata may be relayed in forwarded emails that are forwards of theoriginal electronic communication (e.g., the third email message 204 cin FIG. 2C), and the encoded data may be extracted by an entitydifferent than the original sender (e.g., the third user 210 in FIG. 2C)to perform the action represented by the encoded data.

FIG. 4 is a flowchart of an example process 400 of associating anencoded data with an action, including the encoded data into an outgoingelectronic communication, receiving the encoded data back in an incomingelectronic communication, and carrying out the action indicated by theencoded data. For example, the process 400 could be carried out by anemail client (e.g., an email client in computing system 114 operated byuser 102 of FIG. 1) or an email server (e.g., email server 120 of FIG.1).

An email client of an entity (e.g., the first user 200 in FIGS. 2A-2B)receives 402 an indication to associate an action with an outgoingelectronic communication (e.g., the first email message 204 a in FIG.2A). The indication may be received by any technique, such as receivingan input selection from the user.

The indicated action may be represented by generating 404 encoded data(e.g., the encoded data 208 in FIGS. 2A-2D or the encoded data 310 inFIGS. 3A-3B). The encoded data may be generated by any technique, someexamples of which were provided above in the descriptions of FIGS.3A-3B.

The encoded data that represents the action may be included in anoutgoing electronic communication that is generated 406 by the emailclient. The encoded data may be included in the outgoing electroniccommunication by any technique, such as including the encoded data in amessage header field (e.g., the first message header field 302 a in FIG.3A).

The email client may send the outgoing electronic communication, withthe encoded data, to a first entity (e.g., the second user 202 in FIGS.2A-2D). The email client of the sending entity may then receive 410 anincoming electronic communication (e.g., the second email message 204 bin FIG. 2B) from the first entity. The incoming electronic communicationmay, in some implementations, be a reply to the outgoing electroniccommunication, and may contain the same encoded data that was includedin the outgoing electronic communication.

The email client may carry out 412 the action indicated by the encodeddata that was included in the incoming electronic communication and thatwas extracted from the incoming electronic communication. Some examplesof actions that may be carried out are described above in thedescription of FIG. 2D, and other examples are described below in thedescription of FIG. 7.

FIG. 5 is a flowchart of an example process 500 of using particularemail header fields, such as the Message-ID and In-Reply-To fields, tocarry encoded data (e.g., the encoded data 208 in FIGS. 2A-2D or theencoded data 310 in FIGS. 3A-3B). An email client of an entity (e.g.,the first user 200 in FIGS. 2A-2D) may send 502 a first email messagethat has a Message-ID field (e.g., the first Message-ID field 308 a inFIG. 3A) that includes encoded data representing an identified action.The encoded data could be included in the Message-ID field in any mannerby the email client, for example using techniques described above in thedescription of FIG. 3B.

The email client receives 504 a second email message, which is a replyto the first email message, that has an In-Reply-To field (e.g., theIn-Reply-To field 312 of the second email message 300 b in FIG. 3B) thatincludes the encoded data that was sent in the first email message. Theemail client can extract 506 the encoded data from the In-Reply-To fieldof the second email message.

Implementations are not limited to using the Message-ID and In-Reply-Tofields of email message headers, as any of a number of header fields maybe used, some examples of which were given above in the description ofFIGS. 3A-3B.

FIG. 6 is a flowchart of an example process 600 of an email client of auser (e.g., the first user 200 in FIGS. 2A-2D) including encoded datainto header fields of an email message, receiving the encoded data backin a reply email, and extracting the encoded data to perform an action,according to some implementations. The email client receives 602 arequest from the user to send an outgoing email message (e.g., the firstemail message 204 a in FIG. 2A). The email client determines 604 anaction to be carried out upon receiving a reply to the outgoing emailmessage. The action may be determined by any technique, e.g., receivingan input from the user. The email client generates 606 encoded data thatidentifies the action to be carried out, e.g., in a particular contextin which the action is to be carried out. For example, the context maycorrespond to an email client or server receiving an incoming emailmessage that is in reply to an outgoing email message that the emailclient or server had previously sent. As another example, the contextmay correspond to an email client or server receiving an email messagethat was previously sent by another email client or server. The encodeddata may be generated by any technique, for example using techniquesdescribed above in relation to FIGS. 3A-3B.

The email client can include 608 the generated encoded data into one ormore header fields, such as the Message-ID field (e.g., the firstMessage-ID field 308 a of the first email message 300 a in FIG. 3A), inthe message header of the outgoing email message, send 610 the outgoingemail message. When the email client receives 612 an incoming emailmessage (e.g., the second email message 204 b in FIG. 2B) that is inreply to the outgoing email message, then the email client may extract614 the encoded data from the In-Reply-To field (e.g., the In-Reply-Tofield 312 of the second email message 300 b in FIG. 3B) in the messageheader of the incoming email message. In some implementations, theencoded data may have been automatically included in the In-Reply-Tofield of the incoming email message by an email client of another entity(e.g., the second user 202 in FIGS. 2A-2B) that replied to the outgoingemail message containing the encoded data.

The sender's email client may determine 616 an action to be carried out,based on the encoded data that was extracted from the incoming emailmessage. In some implementations, the action may be determined basedonly on the encoded data, such that the system is stateless, in thesense that the system may not need to store persistent state informationthat is needed in order to translate the encoded data into the action.In some implementations, some state information may be stored betweenemail messages by the email client or server to assist in processing andinterpreting the encoded data extracted from incoming email messages.Regardless of the manner in which the email client determines an actionto be carried out based on the encoded data, the email client mayimplement 618 the action. Examples of actions that may be represented bythe encoded data and implemented by the email client are described withrespect to FIG. 7.

FIG. 7 shows a user interface 700 for selecting an action to be encodedin an email message header (e.g., the first email message header 302 ain FIG. 3A). Other actions could be included besides those shown in FIG.7. A user may be able to select one or more actions to be represented bythe encoded data in an email message, so that the encoded data can beautomatically relayed in subsequent replies and/or forwards of the emailmessage to enable authorized entities to extract and perform the one ormore actions.

For example, the user may select action 702 to prevent the email messagefrom being forwarded to entities outside of a designated group ofentities (e.g., organization 110 in FIG. 1). In some implementations,the encoded data may include a “non-disclosure” flag that could bedetected on forward by a gateway (e.g., server 120 in FIG. 1). If theuser of the user interface 700 sets this “non-disclosure” flag in theencoded data that is included in the Message-ID, for example, then anyunauthorized forwards of the email message to entities outside of theorganization may be detected and blocked by the gateway, based on theflag.

As another example, the user may select action 704 to retain informationabout recipients who are identified in the “Bcc” field of the emailmessage, so that the same recipients can be included in the “Bcc” fieldof subsequent emails that the user sends in the same email thread (e.g.,emails that are related as being replies or forwards of each other). Insome implementations, to avoid undoing the privacy effects of using theBcc field, the email message header could indicate encrypted code namesthat can be translated, by the email client of the user of interface 700(or any other authorized entity extracting the encoded data), into theidentities of the Bcc recipients. As such, when the user (e.g., thefirst user 200 in FIGS. 2A-2D) receives a reply (e.g., the second emailmessage 204 b) to an outgoing email message (e.g., the first emailmessage 204 a) that had one or more recipients indicated in the Bccheader field, and the user composes a third email message in the emailchain, then the third email message can include the same recipients thatwere indicated in the Bcc field of the original email message (e.g., thefirst email message 204 a). For example, the email client operated bythe user can extract the recipients from the encoded data and includethem in the Bcc field of the third email message.

The techniques described here may be used in other ways in the contextof sending and replying to emails that have Bcc (blind carbon copy)recipients. For example, user 1 sends a first email message to user 2and user 3, and also includes user 4 in the Bcc field of the first emailmessage. Using techniques described here, user 1 could specify that theBcc information of user 3 should be encoded and included in the headerof the first email message. User 2 may reply to the first email messageby specifying a “Reply to All” function that sends user 2's reply to allrecipients of the first email message. In some implementations, user 2'semail client or server could extract the encoded data from the firstemail message, determine that user 4 was a Bcc recipient (withoutnecessarily informing user 2 or other users of this fact to retain theanonymity of user 4) and automatically include user 4 in the reply,again as a Bcc recipient. As such, user 4 becomes party to the wholeconversation between user 1 and user 2, but is not visible to otherparties of the conversation (i.e., users 2 and 3). In someimplementations, should user 4, as a Bcc recipient, reply to the firstemail message, then user 4's reply email message would go to user 1, aswell as users 2 and 3, and hence could make users 2 and 3 aware of thefact that user 4 was a Bcc recipient of the first email message. In someimplementations, user 4's email client or server could detect that user4 is attempting to reply as a Bcc recipient and could either indicate awarning to user 4 or could stop the delivery of user 4's reply.

As another example, the user may select action 706 to automatically moveall replies to a designated folder, or action 708 to automatically labelall replies with a designated label, or action 710 to automaticallyforward all replies to a designated email address. These designationscan be encoded in the email message headers of the outgoing emailmessage, and the encoded data will automatically be preserved in anysubsequent replies, at which point the user's email client can extractthe encoded data and perform the designated action. This may reduce theneed for the user to manually establish filters or other rules-basedconfigurations to perform actions on received emails, and instead theuser can specify, directly in the outgoing email message, any actionsthat should be taken on subsequent replies to that email message.

As another example, the user can select action 712 to track emailresponses. If the user sends an email with action 712 selected, thenupon receiving a reply to the email, the user's email client can extractthe encoded data from the email header to automatically locate thepreviously sent email message in the user's email archive, and then markthat original email message as “reply received.” The encoded data couldinclude, for example, a direct pointer to the original email message.For example, if an email client accesses one or more data stores(whether local or remote to the email client) that retain email messagesthat were previously sent and received by the email client, then a datastructure could be configured to include pointers in the form ofaddresses of memory locations within the one or more data stores inwhich the email messages are stored. In some implementations, the user'semail client can be configured to detect any previously sent messagesthat have not yet had a reply received, and flag these to the user. Thiscould reduce the need for a user to manually search for previously sentemails that have not been replied to, as the email client couldautomatically locate previously sent emails using the direct pointer inthe extracted encoded data, and categorize those sent emails.

As another example, the user may select an action 714 to indicate aparticular range of times at which to display (or not display) a replyto the email. For example, the user may not want to see any replies forcertain periods of hours or days (such as evenings or weekends). Othervariations might include time limited actions, such as an action 716 inwhich the user can specify that one or more actions selected for themessage are only valid for a specified period of time, outside of whichthe actions are not performed.

Other examples could include application of certain server-sidepolicies, such as marking a message as high priority (possiblyregardless of what the reply specified), and/or preservation of anyspecial tagging mechanism that the sending server might have.

Another application could be in list servers or social sites, in which asingle generic email address may be used to handle multiple differenttypes of communications. The type of communication could be encoded inthe email message header so that a single email address can be used foractions like member confirmation, moderation, or to indicate that themessage is of a certain type (e.g., for routing or archival purposes,etc.). Such a technique could also enable anonymous emailing, in whichreplies to a single email address can be selectively routed to differentpeople based on the encoded data received in the reply emails.

As another example, encoded data that is included in the header of anemail message could include data from portions of the email messageitself, such as the subject of the message (e.g., from the “Subject”header field), data from the body of the message, or any portion of theemail message. Such information could be used by a sender user of anemail message to detect any changes that were made in those portions ofthe first email message by a replying user. This can improve an emailclient's ability to group related email messages into common threadsdespite edits to the subject line by replying users, and/or to detectchanges made by replying users to the text of sent email messages.

For example, suppose that a first user (e.g., the first user 200 inFIGS. 2A-2B) emails to a second user (e.g., the second user 202 in FIGS.2A-2B) a first message (e.g., the first message 204 a in FIG. 2A) thathas a subject “Report,” and the second user sends a reply message (e.g.,the second message 204 b in FIG. 2B) with an edited subject,“Report—revised.” Typically, the first user's email client may notrecognize that the second message is related to the first message, andmay create a new conversation thread for the second message. But byincluding information indicating the subject of the first email message(e.g., the entire text “Report” from the subject field, or a hash of thesubject field, or a compressed version of the subject field, etc.) intothe encoded data of the first message header (e.g., the encoded data 208in FIG. 2A), the first user's email client can automatically receiveback the subject information of the first message in the encoded data ofthe second message (e.g., the encoded data 208 of FIG. 2B). As such, thefirst user's email client can recognize that the second message belongsto the same conversation thread as the first message, by matching theinformation about the subject “Report” in the encoded data of thereceived second message with subject lines of previously sent messages.

In general, the encoded data could include information indicating anyportion of the first email message, such as the subject of the message,the body of the message, etc. In some implementations, the encodedportions of a first message may be used to help recognize that the firstmessage belongs to the same thread as a second message, even if changeswere made to those portions.

As another example, the encoded data that is included in an emailmessage header could include information related to some portions, orthe entirety, of the body of the email message. When a first user sendssuch encoded data in a first message to a second user and receives, inreply, a second message containing the same encoded data, then an emailclient operated by the first user may extract the information related tothe body of the first email message. This feature may be used for anynumber of purposes. For example, if the second user's email clientembeds the body of the first email message within the body of the secondmessage (e.g., by utilizing a function such as “Include Original Messagein Reply”), then the first user's email client may use the informationrelated to the body of the first email message extracted from theencoded data, and compare it with the body of the first message that isembedded in the body of the second message, to assist in groupingrelated email messages into a common thread, despite possible changes insubject line.

Email clients and/or servers could use any technique to include portionsof the email message into the encoded data. For example, a hash function(e.g., a Secure Hash Algorithm (SHA) such as SHA-256), or other mapping,may be applied to the portions of the email message to generate arepresentation for the entire message or parts of the message. Theresult of the hash function can be included in the encoded data. Asanother example, a digital signature of the portions of the emailmessage may be generated. The digital signature may be included in themessage header and may be accessible by an entity that possesses acredential, such as a public key of a public/private key pair. In someimplementations, the information that represents portions of the emailmessage may be included separately from other encoded data that isincluded in the message header. For example, some or all of theinformation that represents portions of the email message could beincluded in a particular field of the header, as is done with the“DKIM-Signature:” field for a DomainKeys Identified Mail (DKIM)signature.

In some implementations, encoded data that includes portions of theemail message (e.g., as a result of a hash function) could be used tofacilitate access to the portions of the email message. For example, ifuser 1 sends an attachment to user 2 and the user 2 replies, then theencoded data could be used to contain a reference to the originalattachment (e.g., a hash function of the attachment) so that user 1 candetermine which version of the attachment user 2 is replying to. In someimplementations, the encoded data may include the Content-ID headerfield or the Message-ID header field of the email message that includedthe attachment, either additionally or alternatively to including a hashfunction of the attachment.

But independent of the choice of the specific technique used, one ormore portions of an email message can be encoded and included in aheader of the email message. The encoded portions of the email messagecould be used for any purposes, some examples of which are describedabove. As another example, the encoded portions of an email messagecould be used by an appropriately configured email client or emailserver that sends an email message to determine whether the emailmessage was received at a recipient unchanged. This could be used, forexample, to inform the sending email client or server that the recipientreceived the message that it was expected to receive.

As other examples, the encoded portions of the email message could beused to determine information about scenarios in which email messagesare autoresponded-to and/or bounced. This could be used, for example, inenhanced loop detection and/or bounce detection.

In some implementations, improved bounce-handling could be implementedusing the techniques described here. If an email message Delivery StatusNotification (DSN) is returned to a sending user and the DSN containsencoded data that was included in the original email message (e.g., inthe original Message-ID header field), then the user's email client orserver could extract the encoded data out of the DSN and performappropriate bounce handling. For example, in the context of a listserver that operates a mailing list, rather than having a specific emailaddress that applies to all bounced email messages in a list, techniquesdescribed here could be used to allow email messages to be sent withdifferent bounce handling options. Examples of such bounce-handlingoptions include dropping the bounced email message, forwarding thebounced email message to a special email address, or removing a memberassociated with the bounced email address. In some implementations, suchoptions could be achieved with special bounce email addresses such as“list-bounce.” In some implementations, a list server could send normallist email messages with a “drop from mailing list” bounce action butcould send certain email messages (e.g., membership confirm emailmessages) with a “remove member” bounce action. As such, a list servercould implement different types of bounce detection actions fordifferent types of email messages to handle bounced emails differentlydepending on the type of email message that was sent.

In some implementations, improved loop detection could be implementedusing the techniques described here. Such email loops may occur, forexample, as a result of two email clients and/or email serversautomatically sending email messages (e.g., as auto-replies or bouncedemail messages) to each other, creating ongoing replies of emailmessages. Such email loops could be detected by including, in emailmessage headers, encoded data that indicates loop-detection information,such as a count of the number of received email headers, or anidentifier (e.g., an internet protocol (IP) address) for the other emailclient/server. For example, this may be used in addition or as analternative to using the Message-ID to identify such repeated loops.

We have described here some examples of actions that can be representedby encoded data that is included in email messages, and that can beperformed upon extraction of the encoded data by authorized entities.Implementations are not limited to any particular contents of, oractions represented by, the encoded data, as the encoded data could beany transformation of information into a format that is compliant withemail standards.

FIG. 8 is a block diagram of an example computer system 800. Forexample, referring to FIG. 1, one or more parts of the communicationssystem 100 could be an example of the system 800 described here, such asthe computer system (e.g., the computing systems 114, 116, 118 shown inFIG. 1) used by any of the users who access resources of thecommunications system 100, or a server 120 that accesses resources ofthe communications system 100. The system 800 includes a processor 810,a memory 820, a storage device 830, and an input/output device 840. Eachof the components 810, 820, 830, and 840 can be interconnected, forexample, using a system bus 850. The processor 810 is capable ofprocessing instructions for execution within the system 800. In someimplementations, the processor 810 is a single-threaded processor. Insome implementations, the processor 810 is a multi-threaded processor.In some implementations, the processor 810 is a quantum computer. Theprocessor 810 is capable of processing instructions stored in the memory820 or on the storage device 830. The processor 810 may executeoperations such as generating encoded data, sending and receiving emailmessages, extracting the encoded data, and performing actions indicatedby the encoded data (e.g., FIGS. 4-6).

The memory 820 stores information within the system 800. In someimplementations, the memory 820 is a computer-readable medium. In someimplementations, the memory 820 is a volatile memory unit. In someimplementations, the memory 820 is a non-volatile memory unit.

The storage device 830 is capable of providing mass storage for thesystem 800. In some implementations, the storage device 830 is acomputer-readable medium. In various different implementations, thestorage device 830 can include, for example, a hard disk device, anoptical disk device, a solid-date drive, a flash drive, magnetic tape,or some other large capacity storage device. In some implementations,the storage device 830 may be a cloud storage device, e.g., a logicalstorage device including multiple physical storage devices distributedon a network and accessed using a network. In some examples, the storagedevice may store long-term data, such as email archives for users, orsecurity mechanisms (e.g., the key 214 in FIGS. 2A-2D). The input/outputdevice 840 provides input/output operations for the system 800. In someimplementations, the input/output device 840 can include one or more ofa network interface devices, e.g., an Ethernet card, a serialcommunication device, e.g., an RS-232 port, and/or a wireless interfacedevice, e.g., an 802.11 card, a 3G wireless modem, a 4G wireless modem,or a carrier pigeon interface. A network interface device allows thesystem 800 to communicate, for example, transmit and receive emailmessages shown in FIGS. 1 and 2A-2D. In some implementations, theinput/output device can include driver devices configured to receiveinput data and send output data to other input/output devices, e.g.,keyboard, printer and display devices 860. In some implementations,mobile computing devices, mobile communication devices, and otherdevices can be used.

A server (e.g., a server forming a portion of the communications system100 shown in FIG. 1) can be realized by instructions that upon executioncause one or more processing devices to carry out the processes andfunctions described above, for example, generating encoded data, sendingand receiving email messages, extracting the encoded data, andperforming actions indicated by the encoded data (e.g., FIGS. 4-6). Suchinstructions can comprise, for example, interpreted instructions such asscript instructions, or executable code, or other instructions stored ina computer readable medium. A communications system 100 can bedistributively implemented over a network, such as a server farm, or aset of widely distributed servers or can be implemented in a singlevirtual device that includes multiple distributed devices that operatein coordination with one another. For example, one of the devices cancontrol the other devices, or the devices may operate under a set ofcoordinated rules or protocols, or the devices may be coordinated inanother fashion. The coordinated operation of the multiple distributeddevices presents the appearance of operating as a single device.

Although an example processing system has been described in FIG. 8,implementations of the subject matter and the functional operationsdescribed above can be implemented in other types of digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Implementationsof the subject matter described in this specification, such as softwarefor generating, encoding, and extracting encoded data, and performingactions indicated by the encoded data (e.g., FIGS. 4-6), can beimplemented as one or more computer program products, i.e., one or moremodules of computer program instructions encoded on a tangible programcarrier, for example a computer-readable medium, for execution by, or tocontrol the operation of, a processing system. The computer readablemedium can be a machine readable storage device, a machine readablestorage substrate, a memory device, a composition of matter effecting amachine readable propagated signal, or a combination of one or more ofthem.

The term “system” may encompass all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. A processing system caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, softwareapplication, script, executable logic, or code) can be written in anyform of programming language, including compiled or interpretedlanguages, or declarative or procedural languages, and it can bedeployed in any form, including as a standalone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

Computer readable media suitable for storing computer programinstructions and data include all forms of non-volatile or volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks ormagnetic tapes; magneto optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry. Sometimes a server (e.g., forming aportion of a communications facility 100) is a general purpose computer,and sometimes it is a custom-tailored special purpose electronic device,and sometimes it is a combination of these things. Implementations caninclude a back end component, e.g., a data server, or a middlewarecomponent, e.g., an application server, or a front end component, e.g.,a client computer having a graphical user interface or a Web browserthrough which a user can interact with an implementation of the subjectmatter described is this specification, or any combination of one ormore such back end, middleware, or front end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), e.g., the Internet.

Certain features that are described above in the context of separateimplementations can also be implemented in combination in a singleimplementation. Conversely, features that are described in the contextof a single implementation can be implemented in multipleimplementations separately or in any sub-combinations.

The order in which operations are performed as described above can bealtered. In certain circumstances, multitasking and parallel processingmay be advantageous. The separation of system components in theimplementations described above should not be understood as requiringsuch separation.

Other implementations are within the scope of the following claims.

1. A computer implemented method comprising: at a first electroniccommunication system, sending, to an entity, a first email message thatincludes a Message-ID field including data that identifies an action tobe carried out by a second electronic communication system, receiving,from the entity, a second email message that includes an In-Reply-Tofield containing the data that identifies the action to be carried outby the second electronic communication system, and extracting the datafrom the In-Reply-To field in a message header of the second emailmessage.
 2. The method of claim 1, wherein the second electroniccommunication system is the same as the first electronic communicationsystem.
 3. The method of claim 1, wherein the second electroniccommunication system is an electronic communication system other thanthe first electronic communication system.
 4. The method of claim 1,further comprising carrying out the action based on the data extractedfrom the second email message.
 5. The method of claim 1, comprisingreceiving an indication to associate the action with the first emailmessage, and generating the first email message including the data. 6.The method of claim 1, wherein the action to be carried out comprisesexecuting, in a stateless manner, a command that is identified uniquelyby the data and a context in which the action is to be carried out. 7.The method of claim 1, wherein the action to be carried out comprisesaltering a characteristic of the second email based on the data.
 8. Themethod of claim 1, wherein the action to be carried out comprisessending a third email based on the data.
 9. The method of claim 1,wherein the action to be carried out by the second electroniccommunication system was defined based on input received from a user,and the content of the first email message was defined based on inputreceived from the user.
 10. The method of claim 9, wherein the messageheader further comprises security features associating the data with theuser.
 11. The method of claim 1, wherein the first electroniccommunication system or the second electronic communication systemcomprises an email client or an email server.
 12. The method of claim 1,further comprising identifying a third email message previously sent orreceived by the first electronic communication system, and associatingthe third email message with at least one of the first email message orthe second email message.
 13. The method of claim 1, wherein the datafurther includes information that encodes one or more portions of thefirst email message, the one or more portions including at least oneportion of a subject header field of the first email message, or atleast one portion of a body of the first email message.
 14. The methodof claim 13, wherein the information that encodes one or more portionsof the first email message comprises a result of a hash function appliedto the one or more portions. 15-26. (canceled)
 27. A first electroniccommunication system comprising: one or more computers and one or morestorage devices storing instructions that are operable, when executed bythe one or more computers, to cause the one or more computers to performoperations comprising: sending, to an entity, a first email message thatincludes a Message-ID field including data that identifies an action tobe carried out by a second electronic communication system, receiving,from the entity, a second email message that includes an In-Reply-Tofield containing the data that identifies the action to be carried outby the second electronic communication system, and extracting the datafrom the In-Reply-To field in a message header of the first electroniccommunication.
 28. (canceled)
 29. At least one computer-readable storagemedium encoded with at least one computer program comprisinginstructions that, when executed, operate to cause at least oneprocessor in a first electronic communication system to performoperations comprising: sending, to an entity, a first email message thatincludes a Message-ID field including data that identifies an action tobe carried out by a second electronic communication system, receiving,from the entity, a second email message that includes an In-Reply-Tofield containing the data that identifies the action to be carried outby the second electronic communication system, and extracting the datafrom the In-Reply-To field in a message header of the first electroniccommunication.
 30. (canceled)